Process of making cement by the wet method



. 2 Sheet sfSheet 1 Sept. 21 1926.

T RIGBY PROCESS OF MAKING cmmgui s i 'pfis WE? METHOD.

Flled August 28. 1922 Patented Sept. 21, 1925.

T ent e."

rnoonss 0F Mart ns oEraEn'ri'nY THE vrnriuETi-ron Application cfiled August 28, 1922, Serial No 584,849, and in Great Britain September 13,1921.

This invention relates to the manufacture of cement by the wet-method whichinvolves the production of-a' slurry of the admixed materials to be made into cement and this slurry containsoften or thereabouts of water. a

The present invention has as its basic feature the separationfof the drying of a cement slurry from the burning'of the'dried slurry the latter operation being performed as heretofore in an appropriate kiln.(preferabl-y, but not necessarily, of the rotary type) but the slurry being subjected beforehand to evaporative dewatering by means of a steam-heated film drier of the type wherein the evaporation occurs in a closed casing so that-the evaporation space is subst'antially' free from non-con'densible gases.

v In cementmanufacture a large amount of power is required for working the general machinery in connection with the installation and as the steam used in a film drierv 7 can be low pressure steam it is practicable to generate it at high pressure and then to pass it through a steam-driven prime mover from which it exhausts at the "pressure requi-red for heating the drier.

The exhaust steam from the engine can be admitted to the drier at less than atmospheric pressure so that the drier acts as a comparatively low pressure condenser and the condenser proper maintains the neces-" sary low evaporationpressure in the drier. Whateverfthe; form of film-drier used its heating surface of surfaces will. usually most conveniently takethe form of continuouslyrotated internally-heateddrums.

- The heat of the 'kiln eXit gases will pref-- erably be used to generate to as large a clegree as" practicable, the steam to be supplied to a drying plant as referred to, and in that case, such steam may reach the drier as eX- haust from a prime mover driven by such 7 steam;

The material may leave the drier either i as dry'as is possibleby the use of a film drier or it may be dried to a lesser extent so as to contain some 8% or 10% of moisture or thereabouts, or whatever percentage of moisture is desirable. In either of these states it may enter directly the eoolerend of the kiln in the condition of dried powder.

It may, however be made into balls, such pa ovolds, or intobricks of any suitahle size 9;}? any known type .et presa "The accompanying diagrammatic draw'' ings illustrate one form which the inven tion may take. 1

. In the drawings V Figure 1" shows the general arrangement of the principal elements ofa plant for car'- ryingout one form of the process;

Figure 2 shows a plan view ofthe same; Figure 3 indic'atesjin 1 plan a convenient form which the devices" for spreading thick may take;

slurry on: the heating surfaces of the drierv Figure 4 shows how the drums of the drier may be driven. or

I Figure 5 is a'detail, in plan, illustrating means for "s'upplyin'gslurry to the drums, Figure 6 1s a section" on the line-6 6 of 1121116 5; and r l a Figure 7 shows slurry being applied to and removed from one of the drums.

A usualform of rotary ltiln'is indicated at 3the hot exit gases from theco'oler upper end of which pass through boiler fines on.

their way to the stack-*5, and so generate steam" 1n a bo ler 7. This steam'drives', 0r constitutes part of the steam for driving, an

engine9supplyin'g power forthema'chinery' of the cement plant and'thee xhau'st steam from 'wh'l'ch is conducted either directly to face of which drums is s'pread athin film" of slurry containing theingredients of the cement to be burnt in; the kiln-, theslurry containing these as usual in a state of fine division and in the .correct'proportions to produce the cement when-"the dried slurry is burnt in the; kiln.

thus directed into the drier (at a tempera ture ofsay some deg. centigrade) the condenser is the condenserll or, when a process accord- When the steam is t in directi communication I through the valve '17, with the evaporating space of 'the' drier (ii-e. thelspace in which the outer surface of the drums dis-exposed) in which waterivapour isbeing evolved from the slurry film at say some &0 degree'scen-- tigrade.

To keep the diif e 'ence be drums as lowas practicable it is important to distribute the slurry in as thin and uniform a film as may be upon the drums and with this end in View (it being assumed that thick slurry, thick enough to be dealt with satisfactorily onupright drums,

treated each upright drying is being I of which there will customdrum 25,

arily be several in the drier casing, will preferably have co operating therewith .a'smaller internally heated rotary member 27 which by reason of its having an appropriately difi'erent peripheral speed from that of the drum will smooth and even out as a film upon the drum 25 the material escaping out of the bite of the members 25,

27 from the supply duct formed at the back of them by a member 29 bridging the gap between them. A pipe 28 (Figures 4,

'5 and 6) entering the'casingthrough a gland 30 and extending into an aperture in the member 29 supplies slurry to the said duct,

the top and bottom portions of which are closed by end members 82, 34 entering the "bite between the drums 25, 27. The thin film of slurry spread on the drum is removed therefrom, as shown in Figure 7, by

thefmember: 29 as the drum rotates, The dried slurry thus scraped from each drum 25 fallsupon a partition 161, hereinafter 'ymore, specifically referred to, where it is sweptbya scraper orsweep 36 on the drum' '25 towardsvand into aduct 38 from-which it is removedby an automatic discharger 40 of appropriate type, for instance of the kind 'shownfin Figure 1, where the discharger compr ses a rotary member having a serles q of pockets which by rotation ofthe member are presented in turn first to the duct 38 and then to an outlet duct- 42 so that there is a steady intermittent discharge of product without loss of vacuumor pressure :in the casing. Thesteam passing throughithe valve 15 '(Figure 1) and along the pipe'115 (Figures 1 and 6) entersa closed chamber 115* iupon thetop of the unit. Each' drum 25 has its upper spindle'l25 (Figure 6 hollow and passing through a stufiing box 126 on. the

top of the unit, so: that steam passes from thecharnbe'r 115*;into the drum. The vapor generated on the outer surfaces of the drums passes-out of the unit through the pipe 117 that "extends through the chamber 115" and fto the valve 17.

those (252) of the larger drums being of larger diameter than those drums 25. The portions of the hollow spindles'whichcar-ry the gear extend through bearings, including glands 254, 274:, in a partition 161 which sepdensate-receiving space 164 in which latter space the: gears are located, A gear 166 meshes with one of the gears 272 and one of the gears 252 and so drives all the gears and the drums when the shaft 168, on which is mounted the gear 166, is driven by its pulley 170. The condensate flows from the'casing byway of'a barometric pipe 4A the lower end of which is sealed by water in a well 16 provided with a discharge duct The material dried to the required degree is then by suitable conveying means inditinuously operating press indicated at 38 which converts the material into ovoids or blocks and discharges them into the kiln. What I claimasmy inventionand desire to secure by Letters Patent is process of making cement by the wet method that comprises distributing as a a thin uniform film upon a surface of aheating element from which surface the atmos phere 1s excluded a slurry containing the cement materials in the proper proportions to produce the' desired cement when burned, transmitting heat to said film through said element by the condensation on the surface of saidelement opposite tothat on which is the film of steam at a temperature above the boiling point of the water in thefilm and thereby causing generation of water-vapor taining a low vaporpressure on said film, transferring the [slurry thus die-watered to a cement kiln, andtherein burning the ma terial into cement.

i In testimony whereof I aflix my signature.

THOMAS RIGBY.

'arates the evaporating space fromthe concated at31, passed from'the drier to a c0nfrom said film, condensing the vapor thus evolved from the film and thereby main 

